Engine starter



May 21, 1946. E. N. JACOB! ENGINE STARTER Filed Oct. 23, 1944 Paw/WM Edward N Jazz: Z71

Patented May 21, 1946 ENGINE STARTER Edward N. JacobLllflilwaulree, Wis., assignor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Application October 23, 1944, Serial No. 559,898

9 Claims.

This invention relates to engine starters of the so-called automatic type wherein the pinion is automatically propelled into and out of mesh with the ring gear of an engine to be started.

Such a starter has been shown and described in'the co-pending application of Mary C. Fitz- Gerald, executrix' of the estate of John W. Fitz- Gerald deceased, for Engine starter, filed June 19, 1943, Serial No. 491,513,. now Patent No. 2,868,292.

As in all of the automaticitype starters, the pinion is propelled into and out of mesh With the engine ring gear as a result of relative rotation between cooperating threaded parts one of which is drivingly connected with the pinion while the other rotates with the power shaft of the starter.

The present invention differs from the engine starter of the aforesaid co-pending application, however, in the specific manner in which end thrust of the pinion is absorbed and cushioned, and also in the manner in which the driving connection is established between the pinion and its screw threaded actuator.

One of the objects of this invention, therefore, resides in the provision of an engine starter of the character described wherein the translating and torque transmitting connection between the pinion and its actuator includes a nut member threaded on the actuator and splined to the pinion.

Another object of this invention is to provide an engine starter of the character described with novel means reacting between the pinion and nut member for cushioning and absorbing end thrust of the pinion.

A further object of this invention resides in the provision of cup shaped spring washers so designed and arranged as to directly receive and cushion thrust of the pinion with properly proportioned responses both upon improper mesh- .ing of the pinion teeth with those of the engine ring gear and during initial cranking of the engine at which time the starter receives the full load of the engine.

Still another object of this invention is to provide a simplified engine starter assembly capable of being installed as a unit on the power shaft of the starting motor. v

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it'being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment f the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a longitudinal cross sectional view through the starter of this invention showing the pinion in retracted position;

Figure 2 is a view similar to Figure 1 but partly in elevation and partly in cross section and i1- .dicate like parts, the numeral 5 designates the power shaft of a starting motor 6 upon which the starter assemblyindicated generally by the numeral 1 is mounted.

0 eter of the screw threads.

:The. starter unit comprises a tube 8 slipped over I the inner end of .the power shaft and upon which 'the customary pinion 9 is freely rotatable and slidable between stops l0 and II on the tube to define its-operative position of mesh with the ring gear l2 and its retracted position respectively. The stop It in this case is actually the forward end of a pinion actuator l3 which has a hub portion l4 bored to slip over the outer end of the power shaft.

The forward portion l5 of the actuator has a counterbore IE to receive the outer end of the tube 8 and these parts are rigidly joinedtogether at the counterbore as by brazing, indicated generally by the numeral ll.

Preferablytheengaging portions of the tube and actuator are partially threaded as shown at l8 so that the brazing material placed at the bottom unthreaded portion of the counterbore flows into the threaded connection to form a more perfect union between the tube and actuator.

' The forward portion I5 of the actuator has screw threads l9 cut into its exterior and it is to be noted that the outer diameter of the hub portion M of the actuator is less than the root diam- Such proportion of the actuator facilitates machining of its threads by affording clearance for the threading tool during the threading operation.

The connected tube and actuator are anchored to the power shaft 5 for rotation therewith by means of a metal ring 20 brazed or otherwise secured to the hubvof the actuator to reinforce the same and a set screw 2|, passing through a threaded hole in the reinforced hub and entering the shaft as shown. V v V Threaded onto the exterior of the actuator is a nut member 22 adapted to control the motion of the pinion toward-and from mesh with the ring vof the serrations '24 of the nut member.

abutments 32 and. prongs 3| also cooperate withtively heavy thrust of the pinion developed as 7.

member and actuator, and to impart driving torque to the pinion upon interference with forward motion thereof toward the ring gear.

For this purpose, the nut member hasan extension 23 projecting forwardly therefrom toward the rear of the pinion and serrated to form teeth 24 equal in number to those of the pinion and meshing therewith so as to provide a'splinedfj driving connection between the nut member all-3 the pinion.

To keep the diameter of the parts at mum it will be noted that the teeth of the pinion are out down at the rear thereof so :as to provide" stub teeth 25 and to insure a shallow splined connection with the nut member extension. Thus, it

to and extends rearwardly therefrom towardthe nut member to encircle the splined connection between thenut member and pinion. Four circumferentially arranged tang's .2! project from the forward edge 28 of the sleeve and arereceived in the spaces between adjacent pinion: teeth.

These tangs have lateralears 29 projecting into peripheral slots 30 cut into the tops ofrthe regular pinion teeth to thereby cooperate-withthe tangs s3 and the forward edge 28 of the sleeve which abuts the rear of the full-heightpinion'teeth 'asshown to securely anchor the'sleeve'u. In practice the ends of .the tangs 21' are bifurcated and the. bifurcated ends staked into the slots St! to form the lateral ears.-29

Relative axial motion of. the pinion and nut member in a direction away from each other is limited by means ofa seri'es of prongs 3ft sprung inwardly from the wall of the sleeve to engage abutm'ents 32 formed at the'forward extremities The the stop I I to define the limit of rearward motion of the nut member relative to the-actuator.

As stated previously, it is the-function of the nut member '22 to effect .forward propulsion of the pinion toward mesh with the engine ring gear upon relative rotation in one direction between 'it and the actuator.

between anannular abutment on the rearward end of the nut member and therear edge of the sleeve 26 so as to yieldingly resist relative motion of the pinion and nutme-mber toward each-other. The spring 33 has as its function the cushioning of end thrust of the pinion developedboth upon improper meshing of the gears and as the starter picks up the load of the engine.

The spring means herein shown is comprised" adjacent pairs likewise contacting one another to;

form a stack having resiliencies of different value. Thus, the light washers :35 are adapted to yield in response to the relatively light thrust of "the pinion developed by improper ,meshing of the gears while all of the washers yield to the rela- "ctheipinion against the. combined action of the 7 Such motion is imparted to r the pinion by means of spring means 33 confined cranking is initiated. 7

During initial operation of the starter the con nectedypinion and nut member by inertia do not 5 rotate despite rotation of the power shaft and the pinion actuator !3. Since the nut member 22 is drivingly splined to the pinion it follows that relative rotation between the actuator and nut ,member causes the nut member to move forwardly al'ongthe threads of the actuator and to I, ex'e rt a yielding force on the pinion through the spring washers 35 and 36 sufficient to cause the pinion to be propelled into mesh with the engine ring gear.

Upon interference with propulsion of the pinion to .its meshing position "with the ringg'ear such sas'during improper meshing of the gear teeth, the

nut member. continuesto 'move axially forward I and theend thrust of the pinion is absorbed by "the spring washers 35 thus reducing-the noise of improper meshing to a minimum.

Such interference and cushioning of end thrust during. improper meshing of the gears; however, initiates torque, transmission" from the actuator to the pinion and the pinion is caused to'rotate sufficiently to bring :itsv teeth'into register with r those of the engine ring gear atwhich time the expansive force of the washers35 quiclrly meshes the pinion with the ring gear. g 1 V The full meshing positioniofthe pinion with .the ring gear is defined by engagement of the forward endfof the pinion with the stop IDse oured to the inner end-of the"tube' ll and' upon *such interference with its 'forward--.motion the vYnut membercontinues to movforwardly toward spring-washers 35 and 36. Hence, application of the engine load onto the: starteris gradual. and the thrust ofithe pinion effectively.cushioned;

"Obviously when further =compressioniof' the the power shaft E andcranking of the engine results; After the engine starts the pinion is expelled from mesh in the customary manner fiby the overrunning condition at the threaded -connecti'on betweenthe pinion nut member jancl theactuator. T I r 0 "Consequently, it will be seen thatthe'nutmem her is screwedoutwardily, back onto the pinion actuator in a more or lessfree manner until engagement between the abutm'ents132 on the l-nut member with theprongs 3i causes the pinion to be drawn along with the nut member of -mesh withthe ring gear.

Attention is directed to the fact that p'ropul sion of the pinion to its meshing position is made more positive by reason of the 'increased'mass and inertia of the pinion resulting from the weight;

ofthe spring washersbeing added to that of the pinion and nut member.

I From the foregoing description taken in con-1 nection with the accompanying. drawing, it 'will :65. be readily apparent that this invention provides a unitary starter of unique constructionwherein .theparts of the starter are not only held to a desirable minimum but are designed with maximumsimplicity.

'What I claim as my invention-is:

'1. An engine starter of the'character described.

positions with respect to the :r-ing gear ofah .eng'inelto be started; a screw threaded driver;-

at nut member having threads engaged with those Of-thedriver whereby relativefrotation therebetweeneffects axial'movement of the nut member relative to the driver; means'in'cluding the teeth of the'pinion providing'a splineddriving' connection between the nut membefand 'pinion; a shell fixed to the pinion teeth and having an outer diameter substantially no greatenthan that o'f thefpinion 'and'f ,'extended 'from} the pinion teeth toward the nutmem ber st l as to overlie part of the nut membeminterengag'ee able means on the shell and nut. member for limiting relative axial motion between" the pinion and nut member; and a plurality of cupped spring "washers confined in a stack between the" nut member and an abutment on' the shell so as to yieldingly resist relative motion of the pinion and nut member toward each other and through tive position of mesh with the engine ring gear in consequence to relative rotation in one direction between the actuator and nutmember, said spring washers being arranged to cushion end thrust'ofthe pinion developed .upon interference with axial motion thereof toward the engine ring gea1',,certain of said spring washers being of V} relatively light material so as to (yield in 1 advance of the remaining washers inresponse tothe relatively light thrustof thepinion developed upon improper meshing thereofnwith the engine ring gear, but all of said-spring washers being adapted to yieldin response to the relatively heavy thrust of'the pinion developed; as the ,starterpicks up theload of the engine- 2. An engine starter of the character described,

1 comprising: a pinion movable axially along a power shaft'toward and from-mesh with the ring gear of an engine to be started; a screw threaded actuator drivingly connected with the power shaft to rotate therewith; stop means on :the actuator engaged by thepinion to define its retracted powhich the pinion is propelled-toward its operasition; a nut member having threads engaged with those of the actuator whereby relative rotation therebetween effects axial movement of the w nut member relative to the actuator; means on I the nut member cooperating with the teeth of the pinion to provide a splined driving connection between the nut member and the pinion:permitting relative axialmovement therebetween; a

shell fixed to the pinion and extending therefrom to substantially cover said splined connection;

cooperating parts on the shell and-the nut member for limiting relative axial motion of the pinion and the nut member away from each other; and to maintain the splined connectiontherebetween; and spring means confined between the nut member and an abutment on the shell so as to yieldingly resist relative axial movement of the pinion and nut member toward each other and through which the pinion is propelled toward its position of mesh with the engine'ring 'gear'in consequence to relative rotation in one direction between the actuator and nut member, said spring means being operable to cushion the thrust of the pinion developed 'upon interference with axial motion thereof'toward the engine ring gear.

3. An engine starter of the character described.

comprising: a pinion movable axially alo'ng a power shaft toward and from mesh with the ring.

gear of an engine to be'started; stub teeth at the end portion of the pinion remote from the ring gear aligning with the teeth at the forward end of the pinion; a screw threaded actuator drivingly connected with the power shaft so as to rotate-therewith; a nut member having threads engagedwiththose of the actuator whereby relative rotation therebetween effects axial move- -merit of the nut member relative'to the actuator; f teeth "formed" atone end of the nut member and meshing With the stub teeth of the pinion to forma" splined driving connection between the 'nutmember and pinion permitting relative Iongitudinal motion between the pinion and nut member; a shell fixed to thep'inion and extending from said 'end portion thereof to encircle the splined connection between the nut member and pinion; cooperating-abutments 1 on the shell and the nut member for limiting relative axial motion of the pinion and nut memberaway from one another so as to prevent separation of the splined driving connection therebetween; and spring means confined between thenut'member and an abutment on the shell so as to yieldingly resist relative axial movementof the pinion and nut member toward one anothera'rid throughwhich the pinion is propelled toward mesh with the-engine ring gear in consequence torelativ'e rotation in one direction between the actuatorand 'nut member, said spring means being operable to and actuator to the power shaft for rotation therewith; a pinion axially slidable and rotatable onthe tube inwardly of the actuator; anut member having threads engaged with those of the ac 'tuator' whereby relative rotation therebetween efiects axial movement of the nut member relative to' the actuator; a, splined driving connection between the nut member and the pinion permitting relative axial motion of the pinion and nut member toward and from one another; means limiting relative axial motion of the pinion and nut member in a direction away from one another to thereby prevent separation of said splined driving connection; and spring means confined between the nut member and a part on the pinion so as to resistTrelative motion of the pinion and nut member toward each other and through which the pinion is propelled inwardly toward its position of mesh with the engine ring gear in consequence to relative rotation in one direction between the actuator'and nut member.

' 5. In an engine starter having a power shaft:

a tube telescoped over the inner end of the shaft; ,an actuator having a hub telescoped over the outer end of. the shaft and an externally screw threaded inner portion provided with a counter,-

bore to receive a portion of the tube adjacent thereto, the.- hub of the actuator being smaller in diameter than the root diameter of the screw threads of the actuator; means inside said counterbore fixedly joiningcthetube and the actuator:

means for securing the connected actuator and tube to the power shaft for rotation therewith including a separate reinforcing ring encircling the hub of the actuator and, fixed thereto, and, a set screw passing through said ring and the hub of the actuatorfand'enteringrthe shaft; a pinion slidable and rotatable on the tube inwardly of the actuator; a nut member having threads enthe end portion of the pinion remote from of the nut; membenrelativeyto the actuator; -a splined driving, connection between that-nut member and pinion'permitting relative axial motion of the pinion and nut member toward and from each other; means for limiting relative axial motion of the pinion and nut member in a direction away from one another to thereby prevent separationof -said splined driving connection;

compression spring means interposed betweenthe nut member and a part on:the pinion so as to yieldingly resistrelative axial motion of the pin-- ion and 'nut member toward each other and through which the pinion is propelled toward its position of mesh'with the engine ring gear in consequence to relative rotation in'onedirection between the actuator and nutmember; and a pinion rstop mounted on the inner extremity of the tube and against which the pinion abuts to define the neshingrposi-tion of the gears.

6. .-An enginestarter of the'character described, comprising: a pinion movable axially along a power shaft toward and vfrom mesh with the ring gear-of an engine permitting-relative longitudinal motion therebetween; a shell fixed to th pinion and extended therefrom toward the nut member; cooperating abutments on the shell and the nut member for limitingrelative axial movementof the'nut mem ber and pinion awayfrom'one another and act-v ing jointly with said actuator stop means to define. the normal inoperative position of the nut to be started; a screw threaded 5 actuator dr-ivingly connected with the power iaeoogcue ring gear said springvme'anscomprising at least one lightand one heavy-spring element to.-ab-- I sorb light and, heavy5thr-usts .-o f-the pinion respectively. v e 4 8. An engine starter of the'character described,

comprising: a pinion movable axially along apower shaft between retracted andoperative positions with respect to the ring gear of an ,engine to be started; a screw threaded driven-ta the driver whereby relnut member threaded on ative rotation therebetween effects axial movement of the nutmember relative .tojthe driver;

means includingthefteeth of the pinion providing a splined driving connectionbetween the nut member; and spring means confined between 00- 7 operating shoulders on the nut memberand shell to resist-relative longitudinal ion and nut member toward each other and through which the pinion is propelled toward its position of mesh with the engine ring gear upon relative rotation in one direction between the actuator and the nut member. v

7. An engine starter of the character described, comprising: a pinion movable axially along a power shaft toward and from mesh with the ring gear of an engine to be started; stub teeth at the ring gear substantially forming continuations of the teeth at the forward end of the pinion; a screw threaded actuator fixed onthe power shaft to rotate therewith, the end of the actuatoradvjacent to the pinion serving as. a stop to limit motion of the pinion away from the ring gear; a nut member threaded on the actuator; teeth integral with the nut member and extending therefrom in meshing relationship with the stub teeth of the pinion to provide a splined driving.

connection between the nut member and pinion permitting relative iaxial motion therebetween; and spring means 'confined'between abutments on the nut member and pinion to resist relativeaxial motion of. said I parts toward each other and whereby relative rotation in one direction; between the nut memberand actuator effects translation oi the pinion into mesh with the engine motion of the pin-:

member and the pinion; a shell fixed tothe pinion teeth and having an outer diameterx sub stantially .no greater than that of the pinion anjdf extended from the pinionteeth toward the nut member so as to overlie part of the 'nut member; interengageable means on the shell and nut member for-limiting relative axial motion'of the opinion and nut member away from each other; I

and spring meansconfined betweenthe nut member and any abutment onthe shell soa's'to yieldingly resist relative motion of the .pini'on and nut member toward ea'ch other and through which the pinion is propelled toward itsoperativepo sition of mesh with theengine ring gear in conr sequence to relative rotation in one direction be-' tween the actuator and nut member. H l p 9. In an engine starter offthehcharacter described having a rotatable power fshafti ascrew threaded, actuator fixed f on the power shaft J to rotate therewith; a pinion movable axiallyalong the power shaft toward and from mesh Withgtlie I ring gear pram engine to be startedjmeans on the actuator engaged by the pinionuponfaxia1 fmotion' thereof away from the"- en'gine ring gear to determine the" retracted position of -the' pinion; a driving connection betweenthe actuator and the pinion operative to propel the pinion: a'xially intolmesh witlithe engine'rin'g gearpen initial rotation or the actuator and toj therea'fter "transmit cranking torque" to the pinion'ineluding a nut member threaded on the actu'ator, s'tub teeth at the end of the pinion"adjacerit';to the actuatonan extension-on the nut member having relatively shallow teeth formed thereon andm'eshed' with thestub teeth of the pinion so as to provide a "sp'lined driving connection: be-

'tween the'nut member and pinion permitting relative axial motion therebetween, a shell fixed'rto the pinion teeth and extending rearwardly therefrom toward the actuator to encircle said splined "connection and consequently the extension on the nut meinbensaid shell having a diameter substantially no greater than that of the'pinio'n teeth, and spring means interposed between abut- 'ments on the nut member and shell so" as to 'yieldingly resist relative axial motion of the'pin ion and nut member toward -'each"*other and through which the pinion i's 'advanced toward mesh with the'engine-ring gear upon' relative'rotation in one direction between'theactuator and nutmember cooperating abutment on the nut member' teeth and the shell=for limiting relative I axial motion of the pinion and nut member'a'part so as to maintain said splined-connection operative; and a stop on the shaft against Which the pinionabuts to define the operative meshing-positionthereof with the engine ring gear.

- EDWARD N. JACOBL 

